Medical devices including those that may be implanted and those that are worn externally on the body of the patient utilize medical leads to carry signals between circuitry within the medical device and electrodes on distal ends of the medical leads. The medical leads may be used to deliver electrical stimulation pulses from the medical circuitry to the tissue and/or to sense physiological signals from the tissue and convey those signals to the medical circuitry.
Typically, the medical lead is a separate item from the medical device. The lead is routed within the body of the patient to the area where stimulation or sensing is to occur. A proximal end of the lead is connected to the medical device by inserting the lead into a connector enclosure of the medical device. The connector enclosure establishes electrical contact between electrical connectors on the lead and corresponding lead connectors within the connector enclosure. The connector enclosure may provide seals that engage the medical lead and prevent body fluids from entering into the connector enclosure of the medical device.
The connector enclosure of the medical device is often a polymer which is formed over the lead connectors and lead frames that provide a conductor from the electrical connector to electrical contacts on the base of the connector enclosure. The medical device also includes a hermetically sealed can that is typically constructed of a metal such as titanium. The can has feedthrough pins exiting a top of the can that are attached to the electrical contacts of the connector enclosure during assembly of the medical device to complete the electrical pathways from the medical circuitry to the lead connectors of the connector enclosure.
The polymer connector enclosure may have various drawbacks. For instance, the polymer connector enclosure typically requires a significant volume to provide adequate strength. The polymer wall thicknesses are necessarily large enough to adequately support the lead connectors and lead frames present within the connector enclosure, which may inhibit the ability to further miniaturize the medical device. Furthermore, the inner surfaces of the connector enclosure that engage the lead connectors have a relatively large deviation from an ideal inner surface shape. These deviations cause the longitudinal sequence of lead connectors to have relatively large variations in concentricity, which leads to a relatively large lead insertion force and that contributes to lead damage during insertion.